‘Foul and Noxious’: Class Action Alleges Toyota Prius HVAC System Emits Odors, Poses Health Hazard

A proposed class action filed this week claims the heating, ventilation and air conditioning (HVAC) system in certain Toyota Prius vehicles is plagued by a defect that causes the cars to emit “foul, noxious, and/or toxic odors” into their passenger compartments.

The 58-page lawsuit claims Toyota has known for years about the Prius’s propensity to emit a foul odor—which has been described by drivers as “an overpowering urine smell,” a “musty” smell and a “rotten egg or natural gas smell,” while others have likened it to the smell of “a pile of rank, sweaty socks,” sheep, horses, or even band-aids—yet has offered no fix for the apparent problem and no warning to potential buyers and lessees.

The case, filed in California federal court, claims the source of the smell is perhaps even more concerning given it could pose a health risk to drivers and their passengers. According to the complaint, the Prius HVAC system’s defective design allows excess water to collect and fosters “an environment susceptible to the growth of mold and other contaminants.” Mold exposure, the lawsuit argues, can cause upper respiratory tract symptoms in healthy individuals, aggravate asthma and allergy symptoms, and produce “immunological reactions.”

The case claims defendants Toyota Motor Corporation and Toyota Motor Sales, U.S.A., Inc. have gone so far as to conceal the alleged defect from buyers and lessees while failing to address the problem when it manifests. Instead, the costs of attempted repairs have fallen squarely on the shoulders of Prius drivers, who are unaware that no solution exists to completely eliminate the offensive smells, according to the filing.

Meanwhile, Toyota has “exclusive and superior knowledge” of the allegedly defective Prius HVAC system and continues to sell the vehicles while consumers, on the other hand, “[do] not get what they pay for,” the lawsuit alleges.

“A Serious and Real Health and Safety Hazard”

The lawsuit alleges the smell emitted from Toyota Prius models—including the 2006-2020 Toyota Prius, 2017-2020 Toyota Prius Prime, 2010-2015 Toyota PHV, 2012-2016 Toyota Prius C and 2012-2017 Prius V—is linked to a defectively designed HVAC system that allows for the growth of harmful mold and microbial contaminants.

As explained in the complaint, one of the functions of a car’s HVAC system is to cool and dehumidify the vehicle’s interior. When air passes through the system’s evaporator, the refrigerant absorbs heat from the air and produces condensation, which is intended to drain from the HVAC system through a rubber hose, the lawsuit relays.

The HVAC system in the affected Toyota Prius models, however, “fails to adequately remove or drain the condensed water” and instead traps moisture inside, creating an environment in which mold and other contaminants can easily flourish, according to the complaint. Consequently, a “foul, noxious, and/or toxic odor” is produced and makes its way into the affected Prius’s passenger compartment, the suit says.

The case claims the presence of mold inside a car’s HVAC system can lead to serious health issues given mold exposure has been associated “with upper respiratory tract symptoms, coughing, and wheezing in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition.”

Per the case, no reasonable consumer would expect that their car would expose them to foul odors or that Toyota would conceal “a known health and safety hazard.” The lawsuit alleges, however, that the automaker did just that.

Toyota’s Alleged Knowledge of the Defective HVAC System

The complaint claims Toyota has known of the apparent defect in the Prius’s HVAC system since as early as 1997. Indeed, the case says a technical service bulletin issued that year “explicitly acknowledged the presence of microbial growth in the HVAC evaporator caused by dampness in the housing.”

According to the case, Toyota has mentioned the problem in several other technical service bulletins issued throughout subsequent years yet concluded in 2013 that “there is no way to eliminate these odors,” which have apparently also been reported in the Toyota Camry.

The complaint cites a similar lawsuit filed in 2017 in which it was revealed that Toyota had been attempting to make “small, incremental improvements” to the design of the Prius HVAC system but that “none of these engineering changes was sufficient.” One Toyota employee reportedly noted that “a complete solution” to the problem “would require a new design of the HVAC evaporator box for all of our vehicles.”

The lawsuit alleges that although Toyota had “ample opportunity” to disclose the existence of the HVAC defect to Prius drivers and lessees through multiple channels, it has “failed to do so.”

Which Vehicles Are Covered in the Lawsuit?

The case claims the following vehicle models are affected by the allegedly defective HVAC system:

Am I Covered by this Lawsuit?

The case looks to represent anyone in the U.S. (including its territories and the District of Columbia) who purchased or leased one of the vehicles mentioned in the section above.

The lawsuit also proposes to cover a separate group of California residents who purchased or leased one of the covered Prius vehicles or people who purchased or leased their car in California.

How Do I Join the Lawsuit?

There’s usually nothing you need to do to join or be considered part of a class action lawsuit when it’s first filed. The time to take action typically occurs if and when the lawsuit settles, at which point those affected should receive notice of the settlement with instructions on how to claim their piece. 

For now, one of the best things you can do is to stay informed. Check back to this page for any notable updates or sign up for ClassAction.org’s free weekly newsletter here to have class action news and settlement information sent straight to your inbox.